When first applying power to your setup, leave the + wire on the breadboard unplugged.
After you have applied power to the board, then place your finger on the transducer while you plug the + wire back into the breadboard.
If it begins to heat up, unplug the voltage immediately. You have the transducer plugged in backwards and will burn it out very quickly.
To remedy this situation check that the wires are in correctly.You probably have the transducer in backwards.
I almost burned mine up because I forgot to check to see if it was hot.